Vehicle occupant detection systems are useful in connection with air bags and other pyrotechnically deployed restraints as a means of judging whether, and how forcefully, to deploy the restraint. One fundamental parameter in this regard is the weight of the occupant, as weight may be used as a criterion to distinguish between an adult and an infant or small child.
Most prior weight estimation techniques involve installing a pressure sensitive element such as a variable resistance pad or a fluid-filled bladder in or under a vehicle seat cushion, and utilizing the pressure measurement as an indication of occupant weight. See, for example, the U.S. Pat. Nos. 5,474,327, 5,987,370, 6,246,936, 6,101,436 and 6,490,936.
Alternatively, the occupant weight may be measured with one or more strain gauges or load cells that sense the forces (strain or pressure) that the seat applies to a bracket that supports the seat on the vehicle floor. See, for example, the U.S. Pat. No. 5,942,695 and the Publication Nos. 41520, 41542, 41549 and 41559 from the November, 1998 issue of Research Disclosure.